The present application relates to vehicle heating, ventilation and air conditioning (HVAC) systems. In particular, the present application relates to baffles and other structures used to influence air flow through vehicle HVAC systems.
Vehicle HVAC systems may include cabin controls that are used by a vehicle occupant to control the outlet temperature and airflow of the air being delivered into the vehicle cabin from the HVAC system. It may be desirable to configure an HVAC system to provide a linear relationship between the position of a temperature controller and the outlet temperature. For example, when the controller is in a position half way between the coldest and hottest settings, the outlet temperature may be about half way between the coldest and hottest outlet temperatures.
In particular, it may be advantageous to linearize the relationship between the Normalized Temperature (TN) and the controller position. The normalized temperature is defined according to the following formula:TN=(Toutlet−Tmin)/(Tmax−Tmin)where Toutlet is the average outlet temperature when the HVAC system is at a steady state for a given controller position, Tmin is the outlet temperature at steady state with the controller at the full cold position, and Tmax is the outlet temperature at steady state when the controller is in the full hot position.
One way of increasing the linearity of the relationship between controller position and outlet temperature is to position a baffle in the air flow to adjust the airflow characteristics of the system. In some systems that utilize a pivoting temperature door to direct a portion of the air flow over a heater core, a baffle may be positioned downstream from the evaporator.
It would be advantageous to provide an HVAC system having a more linear control relationship between the position of the temperature control and the normalized temperature.